The objective of this research program is to define biochemical defects that may be the fundamental cause of Sudden Infant Death Syndrome. We plan to do more fine structural studies on the pure P-enolypyruvate Carboxykinase from normal livers and SIDS victims. These include "fingerprinting" of tryptic peptides and amino acid analyses. Amino acid sequencing may be undertaken. We will initate a search for changes in the activity of other adaptive enzymes in the livers of SIDS victims. We are especially interested in determining the stability after death of tryptophan pyrrolase and ornithine transcarbamylase which are readily induced and have a short half-life.